Antiretroviral therapy (ART) is effective at lowering HIV-related mortality and reducing transmission among people living with HIV (PLH). Substance use disorders, especially cocaine use disorders (CUDs) greatly reduce ART adherence and persistence on treatment. Because stimulants like CUDs are not amenable to medication-assisted therapy and directly administered antiretroviral therapy is costly and unwieldy in most settings, evidence-based interventions are urgently needed to improve ART adherence and persistence in PLWH with co-occurring CUDs. International guidelines now suggest that the next generation of adherence interventions will need to be scaled back in terms of cost and personnel. Mobile technologies can provide innovative, efficacious and cost-effective strategies to improve ART adherence and optimize HIV treatment outcomes. Such technologies have great applicability in resource-limited settings due to their low cost and ubiquitous nature. Mobil health (mHealth) tools have been shown to improve adherence in patients with various chronic conditions including diabetes, tuberculosis, and HIV; however currently, no published research exists on the impact of mHealth interventions on adherence among PLH and CUDs. Thus, in response to PA- 14-181, mHealth Tools for Individuals with Chronic Conditions to Promote Effective Patient-Provider Communication, Adherence to Treatment and Self-Management, we intend to first conduct qualitative research to assess the acceptability and feasibility of implementing mHealth interventions followed by a pilot feasibility study to examine the effect of mHealth tools on ART adherence. This study is particularly innovative as it proposes to use mHealth intervention with various types of feedback, on PLH with co-occurring CUDs - a group with problematic ART adherence and persistence. The specific aims are: (1) to conduct qualitative assessments using focus groups of PLH who use cocaine and healthcare providers that will assess the acceptability, feasibility, facilitators and barriers of implementing mHealth interventions; and will aid in developing the final design and content of both automated and clinician feedback in preparation for designing a pilot feasibility study; and (2) to conduct a 12-week pilot feasibility RCT among PLH with co-occurring CUDs that will examine the impact of mHealth tools (cellular-enabled smart pill boxes and cell phones) and feedback (no feedback vs. automated feedback vs. automated + clinician feedback) on primary (ART adherence and persistence) and secondary outcomes (HIV viral suppression, cocaine use, retention in HIV care). Findings from this pilot study will help in refining the intervention, developing a research protocol for a future R01 and providing data for a larger-scale RCT. This research will have widespread implications for the use of mHealth tools as an innovative adherence strategy in a population with profound health disparities.